Treatment of clay



?atented Dec. l2, 1922.

amino sm'rss PTEN'E F RE.

Wm mnmna, 0F LONDON, ENGLAND, ASSIGNOR 0F ONE-HAZE 'ro wanna i a PLOWH AN, OF EAST SHEEN, SURREY COUNTY, ENGLAND.

'ETHENT 0F CLAY.

Drawing,

To all whom it may concerm:

Be it hown that 1, WILLIAM Fermenamrmnn, -a subject of the King of England, residing in London, England, have inventt ed certain new and useful Improvements in the Treatment of Clay, of which the following is a specification.

The present invention is for improvements in and relating to the treatment of 10 cla t is known to urifty) clay by suspending it in a 1i uid me rum y aid of a peptising agent, an after subsidence of any impurities to separate the clay substance, for ex- 16 ample by addition to the suspension of a suitab a precipitate, frequentl termed a flocculating agent. The peptlsing or deflocculation reagents hitherto commonly emlo ed will, however, not operatesuccesscase of others the. difference between the minimum and maximum concentration of the deflocculator which will maintain the clay satisfactorily in suspension is too small 85 for convenient working on the commercial scale.

the peptising reagent hereinafter described, a number of clays which are not amenable 80 to treatment by the deflocculators hitherto generally utilized, or which demand comparative close adjustment of the concentration of t ese rea nts, can be successfully treated so as to maintained sufliciently 86 long in suspension to. enable the clay substance to be satisfactorily separated from impurities. and recovered on the industrial scale.

According to this invention, a process for 40 the treatment of claycomprising deflocculation of the clay substance in an aqueous me dium is characterized byvefi'ecting the de flocculation b addition to the clay admixed with water'o a pyro 3 tho-phosphoric acid, or example, metaphosphoric acid, or an alkali salt of metaor pyro-phosphoric acid. I

The clay may .be admixed with a dilute aqueous solution of .meta hosphoric. acid itself, or of this acid in con unction with an alkaline pep agent, such, for example,

as sodium car H y with a number of clays, and in the,

It has now been found that by the use of nic derivative of or- Application filed Kay 5, 1922. Serial No. 658,781.

Alternatively, the clay may he admixed with a dilute aqueous solution containing the pyrophosphate of an alkaline base, such as, for example, a sodium or potassium pyrophosphate.

The clay may be subsequently recovered from its suspension in any desired manner. When flocculation is adopted for this purpose it may prove advantageous to effect this in the manner described in Patent No. 1,324,958 granted in the United States 16th December, 1919.

The following are descriptions by way of example of the operation of the invention.

Example I.

. A Fraddon china clay was worked up with the requisite quantity of soft water to give a 5 per cent mixture, and metaphosphoric acid in the form of an aqueous solution, was added in the proportion of 1 lb. to 1-1- lbs. of the acid for every half ton of clay. The mixture was then allowed to stand as a four foot suspension for about four hours. The clay suspension was run off from the residue, and the clay recovered by the addition to the suspension of an aqueous solut on of alum, in the proportion of 1 lb. of the salt to each pound of metaphosphoric acid employed for defloccu1ation.-

The flocculation was also effected by addition of sodium bicarbonate, in the proportion 11}; lbs. of the salt for each pound of the metaphosphoric acid previously employed.

Example II,

A Canadian china clay from the St. Remi dAmherst district of Quebec, a clay which does not lend itself satisfactorily to suspento itefsnspension of 1 alum in "aqueous .solu

The'mixture was allowed to stand tion, 1} lb. of the salt being used for every 2.; lb. of metaphosphoric acid used in the first instance. 7

Utilizing the same proportion of metaphosphoric acid, i. e. 1} lb. to each half ton of clay, the quantity of sodium carbonate may be increased to 5 lbs. per each half ton of clay, that is to say, in the case of some clays metaphosphoric acid may operate successfully as a peptising agent in the free state as well as in con unction with an al-' kali, but solutions containing salts of the acid with alkaline bases are usually to. be preferred by reason of their more general ap licability. v

t is also preferred to employ the pyro acid in the formof solutions containing its alkali salts, althoughit is possible that the free acid might effectively bring certain clays into suspension.

Emample llj.

A clay from Wotter, Dartmoor, which could not be brought satisfactorily into suspension by treatment with an alkaline pep-.

- tising reagent such as-sodium hydrate, was

' worked up with the. requisite quantity of water to give a 10 per cent mlxture, and

The same clay was also brought into suspension by treatment with acid sodium pyrophosphate, but the separation of the impurities in this case was not so satisfactory as when the normal salt was employed.

E wample I V.

1 ton of Canadian dAmherst clay was mixed with 6-7 tons of water, and 2 lbs. of normal sodium pyrophosphate. was incorporated with the mixture. The latter. was left to stand for four hours in the form of a four foot suspension, and the supernatant suspension of clay was then drawn oil and the clay fiocculated by the addition of 2 lbs.

of alum in aqueous solution.

An increase in the quantity of the pyrohosphate to 20 lbs. gave an equally satisactory result.

Ewample V.

1 ton of Fraddon china clay was admixed with 10 tons of water, and to the mixlessees upon circumstances, such asthe nature of the clay tobe treated, and both the composition of the reagent and theiconcentration thereof may be varied according to need, for, as previously 1ndi cated,a given peptising agent s not necessarily applicable to all clays, nor 1a the concentration appropriate for one clay necessarily appropriate for another, and, in fact, it agent can predicted to be a. deflocculator for clays in general. A simple preliminary explenment, however, sufiioes to disclose the be aviour of the clay towards the deflocculator' and to determine the comp 0- sition and the concentration of the latter necessary for efi'ectin deflocculation.

According to the ardness of the water with which the clay is mixed it may be found necessary appro riately to adjust the proportion relative y to the latter of the deflocculator used for preparing the suspen- $1011.

I olaimz Y 1. The process for the treatment of clay which comprises efiecting deflocculation of the clay substance by mixingthe clay with a dilute aqueous solution'oontaining a solubledpyrogenic derivative of orthophosphoric aci r 2 The process for the treatment of clay WhlCh com rises efi'ecting deflocculation of thaclay su stance by mixing the clay with a dilute aqueous solution containing a p roggnitc derivative of an alkali orthop osp a e.

3 The process for the treatment of clay which comprises effecting deflocculation of the clay substance by mixing the clay with a d lute aqueous solution containing a pyrogemc derivatlve of a sodium hydrogen orthophosphate.

4. The process for the treatment of clay which comprises efiecting deflocculation of the clay su stance by mixing the clay with a dllute aqueous solution containing free alkall and a pyrogenic derivative of a sodium hydrogen orthophosphate.

-5. The process for the treatment of clay which com rises efi'ecting deflocculation of the clay su stance by mixing the clay with a dilutef aqueous solution containing 'an alkali pyrophosphate.

mayebe said that no particular re 6. The process for the treatment of clay 1 84 which comprises'efiecting deflocculation of the clay substance by mixing the clay with a dilute aqueous solution containing a sodium pyrophosphate.

7. The process for the treatment of clay which comprises efi'ecting deflocculation of the clay substance by mixing the clay with a dilute a ueous solution containing sodium pyroplhosp ate and an alkali salt.

8. he process for the treatment of clay which comprises efiecting deflocculation of the clay substance by mixing the clay with a dilute aqueous solution containin a soluble pyrogenic derivative of orthop osplhoric acid, separating the clay suspension om undeflocculated material and recovering the clay from'its suspension.

9. The process for the treatment of clay which comprises effecting deflocculation of the clay substance by mixing the clay with a dilute aqueous solution containing a soluble pyrofenic derivative of orthophosphoric aci separating the clay suspension from undeflocculated material and recovering the clay from its suspension by addition thereto of a flocculating reagent. In testimon whereof I aflix m WIL IAM FELDEN si nature.

EI ER. 

